1. Field of the Invention
The present invention relates to a thermoplastic polyester elastomer and a composition comprising the same. More particularly, the present invention relates to a thermoplastic polyester elastomer which has a high melting point and good water resistance, weather resistance and heat resistance, and a composition comprising the same.
The thermoplastic polyester elastomer of the present invention can be used for the production of various shaped products such as fiber, films, sheets and the like. In particular, it is suitable as a molding material for boots, gears, tubes and the like, and it is useful in applications which require heat resistance, for example, automobiles, electric home appliances, etc. such as joint boots, coatings of electric wires, and the like.
2. Prior Art
Conventional thermoplastic polyester elastomers include a polyetherester elastomer comprising hard segments of polybutylene terephthalate (PBT) and soft segments of polytetramethylene glycol (PTMG) (see JP-B-49-48195 and JP-B-49-31558), a polyesterester elastomer comprising hard segments of PBT and soft segments of polycaprolactone (PCL) (see JP-B-48-4116, JP-A-59-12926 and JP-A-59-1517), a polyesterester elastomer comprising hard segments of PBT and soft segments of dimer fatty acids (see JP-A-54-127955), and the like, and these thermoplastic elastomers are practically used.
When the hard segments comprise PBT, the melting point of elastomers does not exceed 230.degree. C., since the melting point of PBT is less than 230.degree. C. To improve this drawback of the conventional elastomers comprising hard segments of PBT, elastomers are proposed, which comprise hard segments of polyethylene naphthalate or polycyclohexanedimethylene terephthalate having a high melting point (see JP-A-5-202176). However, the content of the hard segments should be 60 wt. % or less from the viewpoint of elastic properties of the elastomers, since soft segments comprise polytetramethylene glycol, and elastomers having a high melting point of 230.degree. C. or higher have not been produced.